Flexible shaft and sheath



- W; H. GATES.

flexible Shaft and Sheath.

A No. 225,516. Patent "l 16,

IN VENTOR Gama MANOR EY.

NPETERS, PNOTO-LITHOGRAFHER, WAsNlNromb c,

UNITED STATES PATENT OFFICE.

WILLIAM H. GATES, OF PHILADELPHIA, PENNSYLVANIA.

FLE XIBLE SHAFT AND SHEATH.

SPECIFICATION forming part of Letters Patent No. 225,516, dated March16, 1880. Application filed December 1, 1879.

To all whom it may concern: Beit known that I, WILLIAM H. GATES, ofPhiladelphia, in the State of Pennsylvania,

have invented certain new and useful Improvements in Flexible Gables orShafts and Shaft-Sheaths for Dental Engines and other Machinery, ofwhich the following is a specification.

My invention is directed to flexible cables or shafts and toshaft-sheaths intended particularly. for dental engines, but alsoadapted to be used in other engines or machinery.

It is my object to obtain a shaft that, with the requisite flexibility,shall be more firm, prompt, and positive in action than the ordinaryshaft heretofore used, and shall not be injuriously affected by thetorsional strain to which it may be subjected.

It is also my object, as regards the sheath or sleeve for enveloping theflexible shaft, to obtain aflexible sheath which shall be lighter andcontain less .metal than the ordinary sheath heretofore employed forthat purpose, and also shall have more resiliency as well asflexibility. The weight of the ordinary sheath is such as to interferematerially with delicacy of manipulation in the use of dental engines,and to tire and fatigue the operator. My improvement obviates this andother defects in the ordinary sheath.

My invention also relates to means for compensating the difference inflexure between the cable and the flexible non-rotating sheath whichordinarily covers it. p

The nature of my invention and the manner in which the same is or may becarried into effect will be understood by reference to the accompanyingdrawings, in which have represented my several improvements in theirpreferred form.

Figure 1 is a perspective view of the fiexi ble shaft and head of adental engine, the hood that covers the driving'pulley being removed anda portion of the sheath being broken away to show the shaft within.Fig.2 is a longitudinal vertical central section of the pulley, head,and part of the shaft and sheath. Fig. 3 is a View, 011 an enlargedscale, of a portion of the shaft and the sheath. Fig. 4 is a transversesection of the shaft. Fig. 5 is a longitudinal vertical central sectionof a shaft in which also coiled spirally around it.

the body-coil is provided with a modified form of filling consisting ofsectional filling-pieces. Fig. 6 is a view of one of the filling-pieces.

The flexible shaft is made up of three parts a bodycoil, A, a wrapper,B, and a flexible filling-core, C. The body-coil A consists of metalribbon, which is by suitable machinery coiled spirally. It is thensupported from within by a continuous coil of line wire, 0, and iscovered by an external metallic Wire, B, The wrapper can be applied invarious ways, its spirals running in the same direction with orpreferably in an opposite direction from the spirals of the body-coil.

The body-coil may be made of a single flat steel strip or ribbon, or oftwo or more such strips laid flat side by side in the same plane andcoiled. In the drawings I have shown it as composed of two strips.

The body-coil, the flexible filling-core G, and the wrapper are formedwhile the metal of which they are composed is tem ')ered. The two formerare then applied to each other and tempered; but the latter, whenpracticable, may be left untempered for the sake of retain ing itsoriginal polish. As each turn of the body-coil is supported by abouteight (more orl'ess) turns of the wrapper, my present experience hasmade the additional strength acquired by tempering the latter seemunnecessary; but as the inner surface of thebody-coil is protected fromoxidation in tempering by the filling-core, so the outer should beclosely wrapped with flne iron wire during that process.

As the softest wire retains a degree of temper and recoil somewhat afterbeing coiled, I have found it convenient to solder the free end of thecore-wire to its mandrel when wound, and then insert it within thebody-coil before releasing. I also form the wrapper separately and ofsuch dimensions that it can only be slipped over the body-coil while thelatter is put under torsion. This application I accomplish readily bytemporarily soldering one end of a mandrelinto one end of the body-coil.The wrapper being slipped on this mandrel and torsion applied to theextremes of mandrel and body-coil, the latter will be slightlycontracted,and the wrapper can then be readily moved to its place on thebody-coil. Upon releasing torsion this external support of the body-coilis perfect.

The flexible filling-core G, formed, as shown in Figs. 2 and 3, of fineclosely-coiled wire inserted in and exactly fitting the bore of thebody-coil A, and extending throughout its length, acts, in connectionwith the borders or edges of the turns or folds of the body-coil whichbear solidly against one another, to firmly support the body-coil and toprevent it from contracting in diameter.

Various forms of filling-core may be employed. That which has just beendescribed is the one which I prefer. I can, however, use the means shownin Figs. 5 and 6, consistin g of short cylinders or sectional filling-pieces with rounded extremities which are inserted in and fit the boreof the body-coil, as represented.

The body of the shaft is thus composed of a tube formed of a coiled flatsteel ribbon or strip, which serves admirably as a powertransmitter, andyet has all needed flexibility, and this steel tube is supportedinternally by a flexible filling-core and externally by a tubularmetallic close-fitting and flexible Wrapper made of wire, preferablyvery fine. v

The flexible non-rotating sheath or casing D, instead of having a bodyof spirally-coiled brass wire, as is usually the case, is provided witha flexible body composed of a thin fiat spirally-wound steel ribbon, 8,covered with any suitable external material, such as the usual chamois,00, which, in turn, is enveloped by an external braided cover, 3 asshown.

This sheath is preferable, on many accounts, to the ordinary sheath. Ireduce the weight to a very great extent, the metal which I use havingless than half the weight of the brass wire in an ordinary sheath of thesame length. I not ofily reduce the weight, which is the most materialitem, but I also lessen the cost of production and obtain a bettersheath in every respect.

To compensate the difference in flexure between the sheath and theflexible cable or shaft which it surrounds, I make that end of it nextto the head E to consist of a two-part sleeve, the two parts F G ofwhich are movable longitudinally with respect to one another.

The part G is a sleeve, which screws upon a tubular externallyscrew-threaded projection, H, on the head or frame E, or is otherwiseattached to said frame. The part F is a metal tube, which can slidelengthwise in the sleeve G, and is provided at its end with a collar orflange, a, by which it is retained within the sleeve, the collar meetinga shoulder at the front end of the sleeve. Between the end of the tube Fand the frame or projection H on the frame is interposed a spiralspring, I. In the frame E is mounted the driving-pulley J, fixed on ahub or short tubular shaft, K, mounted in bearings in frame E. The

rear end of the flexible shaft is soldered or otherwise fastened to acylindrical rod, L, which cal to correspond with the pulleyjournals.

One only of the bearings in this instance is movable. It is formed in orcarried by an arm, M, which at its lower end is fixed to and seated inthe frame E, and is held in place by two binding-screws, On the oppositeside of the frame is a set-screw, g, which projects from the frameagainst the face of the arm M at a point intermediate between thebindingscrews f. By adjusting this set-screw so that it shall'projectmore or less the distance between the arm and the contiguous face of theframe can be varied, and consequently the distance between the twobearings can be increased or diminished at pleasure. This is oneconvenient way of accomplishing the resu'lt. It is manifest, however,that the adjustment of the bearings can be secured in various other waysand by the use of devices which will readily suggest themselves.

The removable covering-hood N fits down over the pulley, as shown inFig. 2. It moves in or on suitable guides g h in the pulleyframe, and isprovided with end slots to permit it to pass down over the upper part ofthe frame.

Having now described my improvements, what I claim, and. desire tosecure by Letters Patent, is-

1. In a flexible shaft or cable, a body-coil composed of aspirally-wound steel ribbon or fiat strip, in combinationv with aflexible filling-core, substantially as set forth.

2. In a flexible shaft or cable, a body-coil composed of aspirally-wound metallic ribbon or flat strip, in combination with anexternal wrapper of closely-wound spirally-coiled fine wire,substantially as set forth.

3. A flexible cable or shaft composed of a tubular body-coil, a wrapper,and a flexible filling-core, substantially as set forth.

4. The flexible sheath composed of a bodycoil of thin flatspirally-coiled metallic ribbon, combined with a suitable cover orjacket, substantially as hereiubefore set forth.

5. In combination with the flexible non-rotating sheath and the frame,the two-part sleeve and the interposed spring, substantially as setforth.

In testimony whereof I have hereunto signed my name this 24th day ofNovember, A. D. 1879.

W. H. GATES.

Witnesses FRANK R. STEVENSON,

SAM. O. WOOLMAN.

